Method and apparatus for aligning a drum assembly used in a video recording device

ABSTRACT

Methods and apparatuses for aligning the component parts of a drum assembly are disclosed. One aspect of the invention relates to tools for measuring and aligning the component parts of the drum assembly. By way of example, the tools may include indicator tools for measuring the relative position of the component parts, as well as alignment tools for aligning the component parts in accordance with the measurements. Another aspect of the invention relates to methods of measuring and aligning the component parts of the drum assembly. By way of example, some methods may pertain to aligning the upper drum and/or the drum support of the drum assembly.

CROSS REFERENCE TO RELATED APPLICATION

This application claims the priority of U.S. Provisional No. 60/250,263filed on Nov. 29, 2000, which is hereby incorporated by reference.

BACKGROUND OF THE INVENTION

The present invention relates to video tape recorders. Moreparticularly, the present invention relates to improved techniques foraligning the component parts of a drum assembly that is used in a videotape recorder.

Video tape recorders that employ rotating record/reproduce head assemblyare well known. In such recorders, tape that is used as the recordingmedium is wrapped partially around a drum assembly that houses therotating record/reproduce head assembly. In general, the head assemblyrotates while the tape is moved (or held stationary) so as to record orreproduce. By way of example, FIG. 1 illustrates a video tape recorder 2that includes a housing 4 for enclosing the components and circuitry ofthe video recording devices. As shown in the cut away portion 6, one ofthe components is a drum assembly 10 having a tape 8 wrapped partiallytherearound. By way of example, representative video tape recordersutilizing a drum assemblies may include models DVW, DNW, HDW Seriesmanufactured by Sony Corporation.

FIGS. 2A & 2B illustrates an exemplary drum assembly 10. FIG. 2A is aperspective view, of the drum assembly 10, and FIG. 2B is a sideelevation view, in cross section, of the drum assembly 10. As shown, thedrum assembly 10 includes an upper drum 12, an inner drum or scanner 14,a lower drum 16, a drum support 18, a spindle assembly 20, an upper base22 and a lower base 24. The inner drum 14, which is disposed inside anopening 26 formed in the upper drum 12, is attached to the spindleassembly 20 via four inner drum screws 28. The inner drum 14, amongother things, includes a plurality of record/reproduce heads 15configured for video recording. The record/reproduce heads 15 aredisposed between the upper and lower drums 12, 16. As should beappreciated, the record/reproduce heads 15 are rotated via the spindleassembly 20 to accomplish any recording or reproducing tasks. The innerdrum 14, also includes a cavity 32 for allowing a slip ring assembly(not shown) to be positioned therein. Slip ring assemblies carryelectrical signals between the rotating heads and other equipment withwhich the rotating head has relative motion. By way of example,representative slip ring assemblies may be found in co-pending patentapplication Ser. No. 09/721,436, which is titled “Slip Ring Assembly ForUse In a Video Recorder” and filed on Nov. 22, 2000, and which is hereinincorporated by reference.

The lower base 24 is structurally coupled to the upper base 22 and theupper base 22 is structurally coupled to the lower drum 16. The drumsupport 18 is configured to hold or support the upper drum 12 relativeto the lower drum 16. For example, as shown, the drum support 18includes an upper drum support arm 36 and a lower drum support arm 38that are attached together via a pair of upper drum support screws 40.Further, the lower drum support arm 38 is attached to a lower surface ofthe lower drum 16 via a pair of lower drum support screws 42 and theupper drum support arm 36 is attached to an upper surface of the upperdrum 12 via a pair of upper drum screws 44. In most cases, the lowerdrum support arm 38 includes an inner peripheral surface 39, which abutsan outer peripheral surface 13 of the upper drum 12. The innerperipheral surface 39 is typically arranged in an arcuate manner. Inorder to ensure contact between the lower drum support arm and the upperdrum, a leaf spring mechanism 45 for biasing them together may beprovided. In addition, the drum support 18 provides a space 30 so as toposition a tape (not shown) along the outer periphery of the drum 10adjacent the recording/reproducing heads 15.

The spindle assembly 20 includes a spindle 46 and a spindle pad 48. Thespindle 46 is rotatably coupled to the upper base 22 via a set ofbearings 52 and powered by a motor (not shown) housed within the lowerbase 24. The motor is typically configured to rotate the spindle 46along an axis 54 at speeds up to 10,000 revolutions per minute (rpm).One end of the spindle pad 48 is attached to the spindle 46 while theopposite end is attached to the inner drum 14. The spindle pad 48includes a guide post 33 and a mounting flange 50. As shown, the guidepost 33 extends into a portion of the cavity 32, and the mounting flange50 provides a mounting surface for securing the inner drum 14 thereto.Furthermore, the guide post 33 includes a guide hole 34 configured forsupporting a slip ring assembly (not shown).

Unfortunately, the design and implementation of the drum assembly leadsto problems which may shorten part life and the proper functioning ofthe video recording device in which it is used. For example, one problemassociated with the above assembly is that the component parts (e.g.,spindle assembly 20, lower drum 16, upper drum 12) of the drum assemblymay become misaligned. As a result of misalignment, excessive vibrationsand/or excessive wear may be encountered during rotation of the spindlewithin the upper and lower drums. In addition, it may be difficult forthe heads 15 to record or reproduce.

In view of the foregoing, there are desired improved methods andapparatuses for aligning the component parts of a drum assembly.

SUMMARY OF THE INVENTION

The invention relates, in one embodiment, to an indicator tool forchecking the alignment of a component of a drum assembly used in a videorecording device. The indicator tool includes a housing. The indicatortool further includes a holding mechanism coupled to the housing andadapted to secure the indicator tool to a second component of the drumassembly. The indicator tool also includes a measuring device coupled tothe housing and adapted to measure the eccentricity of the componentwhen the indicator tool is secured to the second component of the drumassembly.

The invention relates, in another embodiment, to an alignment tool foraligning a support structure of a drum assembly used in a videorecording device. The alignment tool includes an alignment plate adaptedto be secured to a component of the drum assembly. The alignment plateincludes a reference surface, which provides a reference positionrelative to the position of the component of the drum assembly when thealignment plate is secured to the component of the drum assembly. Thealignment tool also includes a positioning mechanism coupled to thealignment plate and adapted to adjust the position of the supportstructure so that the support structure abuts the reference surface ofthe alignment plate. When the support structure abuts the referencesurface, the support structure is placed in the reference positionrelative to the position of the component.

The invention relates, in another embodiment, to an alignment fixturefor aligning a component of a drum assembly used in a video recordingdevice. The alignment fixture allows the drum assembly to be alignedoutside of the video recording device. The alignment fixture includes abase configured to receive and support the drum assembly. The alignmentfixture further includes a reference system configured to place aportion of the drum assembly in a known position relative to the base.The alignment fixture further includes a positioning system foradjusting the position of the component of the drum assembly relative tothe base when the portion of the drum assembly is positioned in theknown position.

The invention relates, in another embodiment, to a method of aligning adrum assembly used in a video recording device. The method includeschecking the alignment of a first component of the drum assemblyrelative to an axis of the drum assembly. The method further includesmaking a determination as to whether the alignment is within a desiredlimit. The method also includes adjusting the position of the firstcomponent relative to the axis when the alignment is not within thedesired limit. The adjusting placing the alignment within the desiredlimits.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is illustrated by way of example, and not by wayof limitation, in the figures of the accompanying drawings and in whichlike reference numerals refer to similar elements and in which:

FIG. 1 is a broken away perspective diagram of a video tape recorder.

FIG. 2A is a perspective diagram of a drum assembly.

FIG. 2B is a side elevation view, in cross section, of the drum assemblyshown in FIG. 2A.

FIG. 3A is a perspective view of an indicator tool, in accordance withone embodiment of the present invention.

FIG. 3B is a side elevation view, in cross section, of an indicatortool, in accordance with one embodiment of the present invention.

FIG. 3C is a side elevation view, in cross section, showing how anindicator tool is used to measure an upper drum, in accordance with oneembodiment of the present invention.

FIG. 3D is a top view showing how an indicator tool is used to measurean upper drum, in accordance with one embodiment of the invention.

FIG. 3E is a side elevation view, in cross section, showing how anindicator tool is used to measure a drum support, in accordance with oneembodiment of the invention.

FIG. 3F is a top view, showing how an indicator tool is used to measurea drum support, in accordance with one embodiment of the invention.

FIG. 4A is a perspective view, of an alignment tool, in accordance withone embodiment of the present invention.

FIG. 4B is a side elevation view, in cross section, of an alignmenttool, in accordance with one embodiment of the present invention.

FIG. 4C is a side elevation view, in cross section, of a biasing screw,in accordance with one embodiment of the present invention.

FIG. 4D is a side elevation view showing how an alignment tool is usedto align a drum support, in accordance with one embodiment of thepresent invention.

FIG. 4E is a top view showing how an alignment tool is used to align adrum support, in accordance with one embodiment of the presentinvention.

FIG. 4F is a side elevation view showing how an alignment tool isaligned, in accordance with one embodiment of the present invention.

FIG. 4G is a top view showing how an alignment tool is aligned, inaccordance with one embodiment of the present invention.

FIG. 5 is a perspective diagram of an alignment fixture, in accordancewith one embodiment of the invention.

FIG. 6 is a flow diagram illustrating a drum alignment procedure, inaccordance with one embodiment of the present invention.

FIG. 7 is a flow diagram illustrating a drum alignment procedure, inaccordance with another embodiment of the present invention.

FIG. 8 is a flow diagram illustrating an alignment checking procedure,in accordance with one embodiment of the present invention.

FIG. 9 is a flow diagram illustrating an upper drum alignment procedure,in accordance with one embodiment of the present invention.

FIG. 10 is a flow diagram illustrating an upper drum positioningprocedure, in accordance with one embodiment of the present invention.

FIG. 11 is a flow diagram illustrating a drum support repositioningprocedure, in accordance with one embodiment of the present invention.

FIG. 12 is a flow diagram illustrating a drum alignment procedure, inaccordance with one embodiment of the present invention.

FIG. 13 is a flow diagram illustrating a drum support measuringprocedure, in accordance with one embodiment of the present invention.

FIG. 14 is a flow diagram illustrating drum support positioningprocedure, in accordance with one embodiment of the present invention.

FIG. 15 is a flow diagram illustrating a drum support alignmentprocedure, in accordance with one embodiment of the present invention.

FIG. 16 is a flow diagram illustrating an alignment tool alignmentprocedure, in accordance with one embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Methods and apparatuses for aligning the component parts of a drumassembly are disclosed. One aspect of the invention relates to tools formeasuring and aligning the component parts of the drum assembly. By wayof example, the tools may include indicator tools for measuring therelative position of the component parts, as well as aligning tools foraligning the component parts in accordance with the measurements.Another aspect of the invention relates to methods of measuring andaligning the component parts of the drum assembly. By way of example,some methods may pertain to aligning the upper drum and/or the drumsupport.

Embodiments of the invention are discussed below with reference to FIGS.3-9. However, those skilled in the art will readily appreciate that thedetailed description given herein with respect to these figures is forexplanatory purposes as the invention extends beyond these limitedembodiments.

Referring first to FIGS. 3A and 3B, an indicator tool 100 will bedescribed, in accordance with one embodiment of the invention. Theindicator tool 100 generally includes a housing 102 for supporting aholding mechanism 104 and a measuring device 106. The holding mechanism104, which is positioned along an axis 107, is configured to secure theindicator tool 100 to the drum assembly 10. In one embodiment, theholding mechanism 104 is used to secure the indicator tool 100 to arotatable component of the drum assembly 10 so as to allow the indicatortool 100 to rotate about the spindle axis 54. For example, the holdingmechanism 104 may be configured to couple the indicator tool 100 to thespindle assembly 20. When connected to the spindle assembly 20, theindicator tool 100 can swivel around the spindle axis 54 via rotationalmovement of the spindle pad 48. In most cases, the axis 107 of theholding mechanism 104 is aligned with the spindle axis 54.

In the illustrated embodiment, the holding mechanism 104 is arranged toengage and couple to the guide post 33 of the spindle assembly 20 (asshown in FIG. 3C). As shown, the holding mechanism 104 includes alocking arm 108, a locking rod 110 and a slotted mount 112. The lockingarm 108 is coupled to the locking rod 110 and the locking rod 110 isthreadably coupled to the housing 102. The locking rod 110 includes abase 113 at one end thereof As shown, the slotted mount 112, which isconfigured for insertion into the guide 34 of the guide post 33, ismechanically disposed between the base 113 and a bottom surface of thehousing 102. In most cases, the outer diameter of the slotted mount 112coincides with the inner diameter of the guide 34. As should beappreciated, the locking arm 108, when rotated, causes the threadedlocking rod 110 to move upwards or downwards (against the housing 102).When moved upwards, the locking rod 110 moves the base 113 against theslotted mount 112 thus causing the slotted mount 112 to bulge outwardly.As a result of the bulging, the slotted mount 112 engages the sides ofthe guide 34 thus securing the slotted mount 112 to the guide 34. Whenmoved downwards, the locking rod 110, moves the base 113 away from theslotted mount 112 thus causing the slotted mount 112 to retain itsshape. As a result of retaining its shape, the slotted mount 112disengages from the sides of the guide 34 thus releasing the slottedmount 112 from the guide 34.

It should be noted that connecting the holding mechanism 104 to theguide 34 is not a limitation, and that the holding mechanism 104 can beconnected to any component that is rotatable about the spindle axis 54.By way of example, the holding mechanism can also be connected to thespindle 46, other portions of the guide post 33, the flange 50 or theinner drum 14. It should also be noted that the holding mechanismconfiguration shown herein is not a limitation and that the connectingmeans may vary according to the specific needs of each device. Forexample, the housing 102 can be connected to the top surface of theinner drum 14 or flange 50 via screws. It should also be noted thatconnecting the indicator tool to a rotatable portion of the drumassembly is not a limitation and that the holding mechanism may beconnected to a stationary portion of the drum assembly. For example, theholding assembly may be configured to mount to the drum support.

The measuring device 106 is configured to measure the relativedisplacement of a surface (e.g., eccentricity) when either the surfaceor the measuring device is moved (e.g., rotated) relative to the other.In one embodiment, the measuring device 106 is used to measure thealignment or eccentricity of the upper drum 112 relative to the spindleaxis 54. In this embodiment, the measuring device 106 measures therelative displacement of the periphery of the upper drum 112 as theindicator tool is swiveled around the spindle axis 54. In anotherembodiment, the measuring device 106 is used to measure the alignment oreccentricity of the drum support 18 relative to the spindle axis 54. Inthis embodiment, the measuring device 106 measures the relativedisplacement of the periphery of the of the drum support 18 as theindicator tool is swiveled around the spindle axis 54.

In the illustrated embodiment, the measuring device 106 is related to adial indicator and therefore it includes an indicator unit 118, ameasuring probe 120 and an output gauge 122. Although not shown, theindicator unit 118 generally houses the inner workings of the measuringdevice. The measuring probe 120 includes an indicator arm 123 having acontact ball 124. The contact ball 124 is configured for contacting thesurface to be measured, as for example, the outer periphery of the upperdrum 12 or the inner periphery of the drum support 18. The measuringprobe 120 is operatively coupled to the indicator unit 118. For example,the indicator arm 123 may be rotatably attached to the indicator unit118 via a pivot and adjustably positioned via a spring mechanism. Theoutput gauge 122, which is also operatively coupled to the indicatorunit 118, is configured to output the displacement of the surface beingmeasured by the probe 120. By way of example, the output gauge 122 maybe a dial or an electronic display (e.g., LCD) showing the relativedisplacement of the probe 120. In most cases, the output gauge 122 isfixed to the indicator unit 118.

In one embodiment, the ball 124 is configured to contact the outerperipheral surface 13 of the upper drum 12. The ball 124 is generallybiased towards the outer peripheral surface 13 of the upper drum 12 bysome spring means (not shown) so as to produce readings in a directionthat is radially aligned and substantially perpendicular to the spindleaxis 54. As such, when the indicator tool 100 is rotated about the axis54 via the alignment shaft/guide connection, deviations (both in anegative and positive direction) along the periphery of the upper drum12 can be ascertained relative to the axis 54. As should be appreciated,deviations between the axis 54 and the periphery at different pointsalong the periphery tend to show the amount of upper drum mis-alignmentor non-eccentricity. Alternatively, the ball 124 may also be arrangedfor contacting an inner peripheral surface of the upper drum 12.

In another embodiment, the ball 124 is configured to contact the innerperipheral surface 39 of the drum support 18. For example, the ball 124may contact the arcing portion of the lower drum support 38 that abutsthe upper drum 12. In this embodiment, the ball 124 is generally biasedtowards the inner peripheral surface 39 of the drum support 18 by somespring means (not shown) so as to produce readings in a direction thatis radially aligned and substantially perpendicular to the spindle axis54. As such, when the indicator tool 100 is rotated about the axis 54via the alignment shaft/guide connection, deviations (both in a negativeand positive direction) along the periphery of the drum support 18 canbe ascertained relative to the axis 54. As should be appreciated,deviations between the axis 54 and the periphery at different pointsalong the periphery tend to show the amount of upper drum mis-alignmentor non-eccentricity.

To elaborate further, the housing 102 is configured to support theholding mechanism 104 and the measuring device 106 in positions that arerelative to one another, for example, a distance X. As shown, thedistance X is the distance between the axis 107 of the holding mechanism104 and the measuring probe 120 (e.g., contact ball 124) of themeasuring device 106. In the illustrated embodiment, the housing 102includes a channel 130 therein for slidably receiving the measuringdevice 106 and a set screw 132 for securing the measuring device 106 inthe channel 130. The set screw 132 may allow the measuring device 106 tobe repositioned relative to the axis 117. That is, by loosening the setscrew 132 the measuring device 106 may be slid within the channel 130 soas to change the distance X. In one implementation, the distance X isadjusted to allow proper contact between the measuring probe and theperiphery (e.g., 13) of the upper drum 12. For example, the distance Xmay correspond to the radius of the upper drum 12. In anotherimplementation, the distance X is adjusted to allow proper contactbetween the measuring probe 120 and the periphery (e.g., 39) of the drumsupport 18. The set screw 132 may also allow the measuring device 106 tobe removed from the housing 102.

In one implementation, the housing may include a nose 134 for protectingthe probe 120 of the measuring device 106 from external forces that maydamage these sensitive components. It should be noted, however, thatthis is not a requirement and that in some cases, it may be necessary toomit the nose 134 from the housing 102 (e.g., when measuring the drumsupport).

FIG. 3C is a side elevation view, in cross section, and FIG. 3D is a topview, showing the indicator tool 100 measuring the outer peripheralsurface 13 of the upper drum 12, in accordance with one embodiment ofthe invention. As shown, the indicator tool 100 is coupled to thespindle assembly 20 through the opening 32 in the inner drum 14 so thatit may rotate about the spindle axis 54. In particular, the slottedmount 112 is secured inside the guide 34 of the spindle pad 48. This maybe accomplished by placing the slotted mount 112 inside the guide 34 andactuating the locking arm 108 so as to cause the slotted mount 112 tobulge inside the guide 34. Furthermore, the measuring probe 120 ispositioned adjacent the outer peripheral surface 13 of the upper drum12. This is generally accomplished by placing the contact ball 124 incontact with the outer peripheral surface 13 of the upper drum 12. Inorder to determine the eccentricity of the upper drum 12, the indicatortool 100 may be rotated about the spindle axis 54 while the ball 124measures the positive and negative displacement of the outer peripheralsurface 13 relative to the spindle axis 54. In one embodiment, theeccentricity of the upper drum 12 is measured by positioning theindicator tool 100 towards a first side 140 of the drum support 18,thereafter zeroing the output gauge 122 at the first side 140, andthereafter rotating the indicator tool 100 along the outer peripheralsurface 114 to a second side 142 of the drum support 18. If theeccentricity is good, then the dial of the output gauge 122 tends toshow a small amount of displacement during rotation. If the eccentricityis not good, then the dial of the output gauge 122 tends to show a largeamount of displacement during rotation.

Rubber bumpers may be positioned towards the first and second sides 140,142 to prevent wear. For example, as shown, rubber bumpers 144 may bepositioned on a top surface of the upper drum 12 to prevent theindicator tool 100 from running into the drum support 18 duringrotation. In one implementation, the rubber bumpers 144 are configuredfor insertion into pre-existing holes in the top surface of the upperdrum 12. In most cases, the rubber stoppers 144 are placed in holesclosest to the drum support 18.

FIG. 3E is a side elevation view, in cross section, and FIG. 3F is a topview, showing the indicator tool 100 measuring the inner peripheralsurface 39 of the drum support 18, in accordance with one embodiment ofthe invention. In this embodiment, the indicator tool 100 does notinclude the nose 134, and the upper drum 12 has been removed from thedrum assembly 10. As shown, the indicator tool 100 is coupled to thespindle assembly 20 through the opening 32 in the inner drum 14 so thatit may rotate about the spindle axis 54. In particular, the slottedmount 112 is secured inside the guide 34. This may be accomplished byplacing the slotted mount 112 inside the guide 34 and actuating thelocking arm 108 so as to cause the slotted mount 112 to bulge inside theguide 34. Furthermore, the measuring probe 120 is positioned adjacentthe inner peripheral surface 39 (e.g., arc) of the drum support 18. Thisis generally accomplished by placing the contact ball 124 in contactwith the inner peripheral surface 39 of the drum support 18. In order todetermine the eccentricity of the arc of the drum support 18, theindicator tool 100 may be rotated about the spindle axis 54 while theball 124 measures the positive and negative displacement of the innerperipheral surface 39 relative to the spindle axis 54. In oneembodiment, the eccentricity of the arc of the drum support 18 ismeasured by positioning the indicator tool 100 towards the first side140 of the drum support, thereafter zeroing the output gauge 122 at thefirst side 140, and thereafter rotating the indicator tool 100 along theinner peripheral surface 39 to the second side 142 of the drum support18. If the eccentricity is good, then the dial of the output gauge 122tends to show a small amount of displacement during rotation. If theeccentricity is not good, then the dial of the output gauge 122 tends toshow a large amount of displacement during rotation.

Referring now to FIGS. 4A-B, a drum alignment tool 200 will be describedin detail, in accordance with one embodiment of the present invention.The drum alignment tool 200 is arranged to align and position the drumsupport 18. That is, the alignment tool 200 provides both a referencesurface that corresponds to the correct position of the drum support 18relative to the spindle axis 54, and a biasing means for positioning thedrum support 18 in the correct position. In the illustrated embodiment,the alignment tool 200, which is configured to couple to the drumassembly 10, includes an alignment plate 202 and a positioning mechanism204. The alignment plate 202 is configured to provide a referencesurface 206 for correctly positioning the drum support 18 relative tothe spindle axis 54. The positioning mechanism 204, on the other hand,is configured to adjust the position of the drum support 18 so that itabuts the reference surface 206 thus placing the drum support 18 in thecorrect position relative to the spindle axis 54.

To elaborate, the alignment plate 202 includes an upper plate 208 and alower plate 210. The lower plate 210 is engageable with the spindleassembly 20 of the drum assembly 10. That is, the lower plate 210includes a wall 211 that defines an opening 213 therein which allows thelower plate 210 to be placed over the guide post 33 of the spindle pad48, and which allows a bottom surface 215 of the wall 211 to interfacewith the flange 50 of the spindle pad 48. The upper plate 210 isconfigured to interface with the drum support 18 (lower drum support 38)during alignment thereof. In one embodiment, the diameter of the upperplate 208 corresponds to the diameter of the upper drum 12. As such, thedrum support 38 can be properly positioned by abutting it (e.g., innersurface 39) against the reference surface 206 of the upper plate 208.The alignment plate 202 also includes a plurality of screw holes 217therethrough. The screw holes 217 are oriented such that the inner drumscrews 28 may be used to couple the alignment plate 202 to the spindleassembly 20. When coupled, the alignment plate 202 is substantiallyaligned with the spindle axis 54. In addition, the alignment tool 200may rotate via the spindle pad 48.

The positioning mechanism 204 is configured to adjust the position ofthe drum support 18 relative to the spindle axis 54 when the alignmentplate 202 is aligned with the spindle axis 54 and coupled to the spindleassembly 20. In one embodiment, the positioning mechanism 204 isconfigured for positioning the drum support 18 adjacent the upper plate208. The positioning mechanism 204 is coupled to the alignment plate202. In the illustrated embodiment, the positioning mechanism 204includes an alignment bracket 211 that is detachably coupled to theupper plate 208 via a mounting insert 212 and a mounting screw 214. Asshown, the mounting insert 212, which fits into a cavity 216 in theupper plate 208, includes a hole for allowing the mounting screw 214 tobe placed therethrough. The mounting screw 214 treadably couples thealignment bracket 218 to the upper plate 208. The threaded connection,as well as, the engagement between the mounting insert 212 and thecavity 216, is preferably located at the center of the upper plate 208so that the center of the mounting insert 212 is aligned with thespindle axis 54.

When coupled to the upper plate 208, the alignment bracket 218 isconfigured to place a flange 220 having a biasing screw 222 threadablycoupled thereto across from the outer peripheral surface 224 of theupper plate 208. In one embodiment, the alignment bracket has a lengthL, i.e., the distance between the flange 220 and the threaded connection(e.g., spindle axis 54), that places the flange 220 and thus the biasingscrew outside the outer periphery of the drum support 18 when thealignment plate 202 is attached to the spindle assembly 20. The biasingscrew 222, which has a contact ball 225 at one end, is configured forapplying a force to the drum support 18 so as to move the drum supporttowards the alignment plate 202. That is, the biasing screw (whenrotated) works against the flange 220 to push the drum support 18towards the upper plate 208 of the alignment plate 202. As such, thedrum support 18 can be correctly positioned via the biasing screw 222.The correct position generally corresponds to the condition where theinner peripheral surface 39 of the drum support 18 (e.g., arc) abuts theouter peripheral surface 224 of the upper plate 202.

In one embodiment, the biasing screw 222 is arranged to be the givepoint when a force is applied the drum support 18. Referring to FIG. 4C,the biasing screw 222 may include a spring means 240 for allowing theball 225 to give in the direction of the applied force. In otherembodiments, the biasing screw may have a first turning position forapplying the force and a second position for removing the force so asreduce damage caused by excessive turning (a limiter).

FIG. 4D is a side elevation view, in cross section, and FIG. 4E is a topview, showing the alignment tool 200 positioning the drum support 18, inaccordance with one embodiment of the invention. As shown, the upperdrum 12 and inner drum 14 are removed from the drum assembly 10, and thealignment tool 200 is coupled to the spindle assembly 20. In particular,the alignment plate 202 is secured to the spindle pad 48. This may beaccomplished by placing the lower plate 210 over the guide post 33 andconnecting the screws 28 to the flange 50. Furthermore, the biasingscrew 222 is positioned adjacent the outer peripheral surface 41 of thedrum support 18. This is generally accomplished by placing the mountinginsert 212 in the cavity 216 of the upper plate 208 and connecting themounting screw 214 to the upper plate 208 so as to couple the alignmentbracket 218 to the upper plate 208, and thereafter rotating the flange220 proximate the drum support 18. Once the flange 220 is proximate thedrum support 18, the position of the drum support 18 can be adjusted viathe biasing screw 222. This may be accomplished by loosening the lowerdrum support screws 42, and actuating the biasing screw 222 until thedrum support 18 abuts the upper plate 208 of the alignment drum 200. Asshown, the positioning mechanism 204 essentially sandwiches the drumsupport 18 between the biasing screw 222 and the upper plate 208. Oncepositioned, the lower drum screws 42 may be tightened thus leaving thedrum support 18 in the correct position (e.g., aligned).

In an alternate embodiment, the drum assembly 10 can be modified toinclude a second positioning mechanism so as to move the drum supportaway from the spindle axis. This may be needed to back the drum supportaway from the alignment plate. It may also be needed to make adjustmentswhen an alignment plate is not used. Referring to FIG. 4D, for example,a second positioning mechanism 230 is shown. The second positioningmechanism 230 includes a set screw 232 that is threadably coupled to thedrum support 18. The set screw 232 is adapted to move through the drumsupport 18 so as to engage the outer peripheral surface of the lowerdrum 16. As should be appreciated, the lower drum 16 is fixed, and thuswhen the set screw 232 engages the lower drum 16, the drum support 18 ispushed away from the spindle axis 54.

FIG. 4F is a side elevation view, in cross section, and FIG. 4G is a topview, showing how the drum alignment tool 200 is aligned, in accordancewith one embodiment of the present invention. This is generally done toensure the proper positioning of the drum support, i.e., if theeccentricity of the alignment tool is off then the drum support may notbe positioned correctly when it abuts the alignment tool. Theeccentricity of the alignment tool 200 is generally checked using ameasuring device 300. By way of example, the measuring device 300 may bea dial indicator, which is well known to those skilled in the art, or itmay be the measuring device 106, which is shown in FIG. 3. As shown, themeasuring device 300 includes a measuring probe 302 that includes a ball303 for contacting the reference surface 206 of the upper plate 208, anindicator unit 304 and a gauge 306 for outputting the measurements. Themeasuring device 300 is generally connected to a fixed surface 308during measurements. By way of example, the fixed surface 308 may be thelower drum 16, a grounded surface, a portion of the video recordingdevice 2 or a fixture configured for holding the drum assembly 10outside the video recorder 2.

The measuring device 300 is typically held in a fixed position. As such,when the alignment tool 200 is rotated about the spindle axis 54,deviations along the periphery of the alignment tool 200 can beascertained relative to the spindle axis 54. As should be appreciated,deviations between the axis 54 and the periphery tend to show the amountof mis-alignment or non-eccentricity. In one embodiment, a force mayapplied to the alignment tool, towards the measuring device 300, toadjust its position. As shown in FIG. 4G, for example, when thealignment tool is out of position (shown by dotted lines 330) a force Fmay be exerted on the alignment tool to move it into the correctposition. The force may need to be applied in many iterations. In oneimplementation, the force F is exerted by a finger. In anotherimplementation, the force F is exerted by a positioning mechanism.

FIG. 5 is a perspective diagram of an alignment fixture 350, inaccordance with one embodiment of the invention. The alignment fixture350 allows the drum assembly to be aligned outside of the videorecorder. The alignment fixture 350 includes a base 352, which issupported by a plurality of legs 354. The legs 354 may be fixed to thebase 352 using any suitable means. In the illustrated embodiment, thereare four legs that fastened to the corner regions of the base 352 viascrews 356. The base 352 includes a drum assembly opening 358 forreceiving a portion of the drum assembly 10, and a top surface 360 forsupporting the drum assembly 10 therein. In one embodiment, the topsurface 360 is configured to support at least a portion of the bottomsurface of the lower drum 16. The base 352 may include mounting threads362 for securing the drum assembly 10 to the base 352 via screws (notshown) placed through the drum assembly 10. For example, referring toFIG. 2A, screws may be placed through holes 71 so as to secure the drumassembly 10 to the base 352.

The alignment fixture 350 also includes reference pins 364 for guidingthe drum assembly 10 into the correct position relative to the base 352.The reference pins 364 are generally positioned around the opening 358so that they each engage and/or abut the side (e.g., outer peripheralsurface) of the lower drum 16 when the drum assembly 10 is placed in theopening 358 and on the top surface 360 of the fixture 350. Alternativelyor additionally, the base 352 may include an alignment pin 366 forguiding the drum assembly 10 into the correct position relative to thebase 352. The alignment pin 366 is generally positioned so that itengages the bottom surface of the lower drum 16 when the drum assembly10 is placed in the opening 358 and on the top surface 360 of thefixture 350. In one embodiment, the alignment pin 366 extends from thetop surface 360 of the base 352 so that it may be inserted intoalignment holes (not shown) in the bottom surface of the lower drum 16.By using the reference pins and alignment pins, the drum assembly can bepositioned in a known position relative to other components of thefixture. This is advantageous for adjusting the positions of variouscomponents of the drum assembly 10 so as to improve eccentricitythereof. In one embodiment, the known position corresponds to thespindle axis 54 of the drum assembly thereby allowing the components ofthe drum assembly 10 to be positioned relative to the spindle axis.

The fixture 350 also includes a positioning system 368 for adjusting thepositions of various components of the drum assembly 10 when the drumassembly 10 is secured to the base. In one embodiment, the positioningsystem 368 includes a first positioning mechanism for adjusting theposition of the upper drum 12. The first positioning mechanism includesa pair of adjustment posts 370 and 372, and a pair of adjustment screws374 and 376. The adjustment posts 370 and 372 are coupled to the base352 and extends upwards therefrom. By way of example, the posts may becoupled to the base via screws. The adjustment screws 374 and 376 arethreadably coupled to the adjustment posts 370 and 372, respectively.That is, each of the first adjustment posts 370 and 372 includes athread for receiving a threaded portion of the adjustment screws 374 and376. As shown, the adjustment screws 374 and 376 may include a tactilefeature 378 and an abutment feature 380, which are located at oppositeends of the adjustment screw. The tactile features 378 allow a user torotate the adjustment screws 374, 376 within the adjustment posts 370,372, and the abutment feature 380 provides a surface for engaging someportion of the upper drum 12 or some component coupled to the upper drum12 when the adjustment screws 374, 376 are moved through the adjustmentposts 370, 372.

In one embodiment, the adjustment screws 374, 376 when actuated withintheir respective threads are configured to engage and exert a force F onthe upper drum 12 so as to adjust its position. This is generallyaccomplished when the upper drum support screws 40 have been loosened soas to allow movement of the upper drum 12 relative to the lower drumsupport 38. Any suitable configuration of the adjustment posts andadjustment screws may be used. In the illustrated embodiment, theadjustment posts 370, 372 are positioned on the base 352 and theadjustment screws 374, 376 are positioned on the posts 370, 372 so thatthe adjustment screws 374, 376 engage the upper drum support 36, whichis coupled to the upper drum 12. The threads of the adjustment posts370, 372 are generally aligned along the same axis so that theadjustment screws 374, 376 may be placed in an opposed relationship.That is, the first adjustment screw 374 is configured to apply a firstforce F1 in a first direction, and the second adjustment 376 screw isconfigured to apply a second force F2 in a second direction, which isopposite the first direction. As such, when the upper drum supportscrews 40 are loosened, the adjustment screws 374, 376 may be used toreposition the upper drum 12, i.e., the upper drum may be moved back andforth via F1 and F2 until the correct position is obtained.

It should be noted that engaging the upper drum support 36 is not alimitation and that other parts of the upper drum 12 may be engaged. Forexample, the adjustment screws 374, 376 may be configured to engage theouter peripheral surface 13 of the upper drum 12. In cases such asthese, it is generally desirable to have the adjustment screws 374, 376positioned across one another such that their axis crosses through thecenter of the spindle axis 54.

In another embodiment, the positioning system 368 includes a secondpositioning mechanism for adjusting the position of the drum support 18.The second positioning mechanism includes a pair of spaced apartpositioning set screws, which are threadably coupled to the base. Thatis, the base 352 includes first and second threads for receiving a firstpositioning set screw 382 and a second positioning set screw 384.Although not shown in detail, the first and second threads extend fromthe side of the base 352 to the opening 358 in the base 352 so as toallow the set screws 382, 384 to extend into the opening 358 whenactuated (e.g., rotated).

The positioning set screws 382, 384 when actuated within theirrespective threads are configured to engage and exert a force F on thedrum support 18 so as to adjust its position. Any suitable configurationof the positioning set screws may be used. In the illustratedembodiment, the positioning set screws 382, 384 are positioned on thebase 352 so that they engage the lower drum support 38. The threads inthe base 352 are generally parallel to one another and positioned inaccordance with a first and a second side 140, 142 of the drum support18. For example, the first set screw 382 is configured to engage thefirst side 140 of the drum support 18 and the second set screw 384 isconfigured to engage the second side 142 of the drum support 18. Assuch, the alignment of the drum support 18 may be manipulated by movingthe set screws 382, 384 into engagement with the drum support 18 andforcing the drum support 18 into a new position. In one embodiment, theset screws 382, 384 are actuated by the same amount so as to move thedrum support 18 uniformly. In another embodiment, the set screws 382,384 are actuated by different amounts so as to move one side of the drumsupport 18 more than another side 18. This is generally done to improvethe eccentricity of the arc of the drum support.

In another embodiment, the positioning system 368 includes a thirdpositioning mechanism for adjusting the position of the drum alignmenttool 200 when the drum alignment tool 200 is secured to the spindleassembly 20 of the drum assembly 10. The third positioning mechanismincludes a measurement post 388 and a third adjustment screw 390, whichis threadably coupled to the second adjustment post 372. The measurementpost 388 is coupled to the base 352 and extends upwards therefrom. Byway of example, the post 388 may be coupled to the base via screws. Thepost 388 is arranged to allow a measurement device to engage a surfaceof the alignment drum 200 or a component of the drum assembly 10. Asshown, the measurement post 388 is configured to receive a measurementdevice 392. Any suitable measurement device may be used. In theillustrated embodiment, the measurement device 392 corresponds to themeasurement device 106 of the indicator tool 100 shown in FIG. 3. Assuch, when the measurement device 106 is removed from the housing 102,the measurement device 106 may be placed in a groove 394, which isdisposed in one end of the post 388, and which is similar to the channel130, i.e., the measurement device 106 is slidably received in the groove394. The measurement post 388 may include a securement means 396 (e.g.,set screw) for holding the measurement device in the groove.

With regards to the third adjustment screw 390, when actuated within itsrespective thread, it is configured to engage and exert a force F on thedrum alignment tool 200 so as to adjust its position. Any suitableconfiguration of the third adjustment screw may be used. In theillustrated embodiment, the third adjustment screw 390 is positioned onthe post 388 so that the third adjustment screw 390 engages referencesurface 206 of the drum alignment tool 200 when it is coupled to thespindle assembly 20 as shown in FIG. 4. Furthermore, the thread of theadjustment post 372 is generally aligned with the groove 394 of themeasurement post 388. As such, when the lower drum support screws 40 areloosened, the third adjustment screw 390 maybe used to reposition thedrum support 18 while the measuring device measures the displacement ofthe drum alignment tool 200 relative to the spindle axis 54. In mostcases, this is accomplished when the measuring device 106 measures anegative displacement that is towards the third adjustment screw 390,i.e., the alignment drum may be moved in a positive direction towardsthe measuring device until the correct position is obtained.

In another embodiment, the positioning system 368 includes a fourthpositioning mechanism for adjusting the position of the inner drum 14 ofthe drum assembly 10. For example, the fourth positioning mechanism maybe used to position the inner drum 14 relative to the spindle axis 54.The fourth positioning mechanism includes the measurement post 388, anda fourth adjustment screw 398, which is threadably coupled to the secondadjustment post 372. The fourth adjustment screw 398 when actuatedwithin its respective thread is configured to engage and exert a forceF₄ on the inner drum 14 so as to adjust its position. Any suitableconfiguration of the fourth adjustment screw may be used. In theillustrated embodiment, the fourth adjustment screw 398 is positioned onthe post 372 so that the fourth adjustment screw 390 engages the outerperipheral surface of the inner drum 14. Furthermore, the thread of theadjustment post 372 is generally aligned with the groove 394 of themeasurement post 388. As such, when the screws 28 are loosened, thefourth adjustment screw 398 may be used to reposition the inner drum 14while the measuring device 106 measures the displacement of the innerdrum 14 relative to the spindle axis 54. In most cases, this isaccomplished when the measuring device 106 measures a negativedisplacement that is towards the adjustment screw, i.e., the alignmentdrum may be moved in a positive direction towards the measuring deviceuntil the correct position is obtained.

It should be noted that the above configuration of the fixture is not alimitation and that the fixture can take many forms. For example, thebase 352 may include a recess 400 for placement of parts such as screws.In addition, the base 352 may include a hole 402 for receiving auxiliarytools used to help align the drum assembly. The hole 402 is generallyconfigured to receive an auxiliary tool post similar to the posts 370,372 or 388.

In one embodiment, the auxiliary tool is a reference guide for providinga tangent surface. The tangent surface may be arranged to abut any oneof the components of the drum assembly or alignment tools so as toimprove eccentricity. For example, the tangent surface may be set at apredetermined distance relative to the spindle axis. In oneimplementation, the position of tangent surface relative to the spindleaxis corresponds to the distance of the outer peripheral surface of thealignment drum relative to the spindle axis. In another implementation,the position of tangent surface relative to the spindle axis correspondsto the distance of the outer peripheral surface of the upper drumrelative to the spindle axis. In yet another implementation, theposition of tangent surface relative to the spindle axis corresponds tothe distance of the outer peripheral surface of the spindle relative tothe spindle axis.

In another embodiment, the auxiliary tool is a head tip projection toolfor measuring the position of the heads of the inner drum relative tothe spindle axis. By way of example, the head tip projection tool may besimilar to the measurement post 388. That is, the head tip projectiontool may include a post for insertion into the hole and a groove forreceiving a measuring device. The post is generally configured toposition the measuring device adjacent the heads of the inner so thatthe indicator arm abuts the outer peripheral surface of the heads.

FIG. 6 is a flow diagram illustrating a drum alignment procedure 500, inaccordance with one embodiment of the present invention. Prior tostarting the alignment procedure 500 conventional pre-alignment stepsmay be performed. For example, some pre-alignment steps may includeremoving a top machine cover, an elevator cover, and/or a transport trimcover. In addition, other pre-alignment steps may include removing arotary head cleaner assembly, an upper drum cover, and/or brush/slipring assembly. These pre-alignment steps are readily understood by thoseskilled in the art and for the sake of brevity will not be discussed ingreater detail. It should be noted, however, that some of these stepsare described in a maintenance manual distributed by the Sony Corp. andtitled, “Digital Videocassette Recorder DVW-A500/500” (1^(st)Edition—Revised 3), which is herein incorporated by reference. Moreover,the pre-alignment steps may include removing the drum assembly from thevideo recorder, and placing the drum assembly in a fixture.

The alignment procedure 500 begins at step 502 where the alignment oreccentricity of the upper drum 12 is checked relative to the spindleaxis 54. This is typically accomplished using an indicator tool such asa dial indicator or the indicator tool 100 shown in FIG. 3. In oneembodiment, a measuring device is rotatably positioned relative to thespindle axis 54 and a measuring probe is set at a peripheral surface ofthe upper drum 12. Once positioned, the alignment or eccentricity of theupper drum 12 is measured via the measuring probe by rotating themeasuring device about the spindle axis 54. When using the indicatortool 100, the indicator tool 100 is positioned on the spindle pad 48 andthe measuring probe 120 is set at the outer peripheral surface 13 of theupper drum 12 (see FIGS. 3C and 3D). It should be noted, however, thatthis is not a limitation and that other embodiments may includepositioning the indicator tool 100 relative to the inner drum 14 or evenrelative to the spindle 46. In yet other embodiments, the probe may beset relative to the inner peripheral surface of the upper drum 12.

Subsequent to step 502, the process flow proceeds to step 504 where adetermination is made as to whether the upper drum 12 is aligned (yes)or mis-aligned (no). If the determination is that the upper drum 12 isaligned (or eccentric) then the process flow ends. If the determinationis that the upper drum is mis-aligned (or non eccentric) then theprocess flow proceeds to step 506. In general, the determination is made(as the indicator tool is rotated) by deciding whether or not thedeviation of the probe is within a desired limit. By way of example, ithas been found that a maximum deviation of 0.0002 inches (two divisionson the dial indicator) works well. It should be noted, however, thatthis is not a limitation and that the amount of deviation may varyaccording to the specific needs of each device.

In step 506, the upper drum 12 is aligned relative to the spindle axis54. This is generally accomplished by adjusting the position of theupper drum 12 relative to the spindle axis 54. In one embodiment, theposition of the upper drum 12 is adjusted by repositioning the upperdrum support 36 relative to the lower drum support 38. This may beaccomplished by loosening the upper drum support screws 36, moving theupper drum 12 to the desired position, and tightening the upper drumsupport screws 36 while maintaining the desired position.

Following step 506, the process flow proceeds to step 508 where thealignment or eccentricity of the upper drum 12 is checked relative tothe spindle axis 54. This step is analogous to step 502 above. Forexample, the measuring device is rotatably positioned relative to thespindle axis 54 and the measuring probe is set at a peripheral surfaceof the upper drum 12. Once positioned, the alignment or eccentricity ofthe upper drum 12 is measured via the measuring probe by rotating themeasuring device about the spindle axis 54.

Subsequent to step 508, the process flow proceeds to step 510 where adetermination is made as to whether the upper drum 12 is aligned (yes)or mis-aligned (no). This step is analogous to step 504 above. Forexample, if the determination is that the upper drum 12 is aligned (oreccentric) then the process flow ends. In addition, if the determinationis that the upper drum 12 is mis-aligned (e.g., if not able to centerthe upper drum assembly within 0.0002 inches) then the process flowproceeds to step 512. Again, the determination is made (as the indicatortool is rotated) by deciding whether or not the deviation of the probeis within a desired limit.

In step 512, the drum support 18 is aligned relative to the spindle axis54. This is generally accomplished by adjusting the position of thelower drum support 38 relative to the spindle axis 54. In most cases,the lower drum support 38 is adjusted after the upper drum 12 has beenremoved. In one embodiment, the position of the lower drum support 38 isadjusted by repositioning the lower drum support 38 relative to thelower drum 16. This may be accomplished by loosening the lower drumscrews 42, moving the lower drum support 38 to the desired position, andtightening the lower drum screws 42 while maintaining the desiredposition. In one embodiment, the lower drum support 18 is alignedwithout using the drum alignment tool 200. In another embodiment, thelower drum support 18 is aligned using the drum alignment tool 200. Inthis embodiment, the alignment tool 200 shown in FIG. 4 generally actsas a guide for determining the desired position of the lower drumsupport 38. For example, the alignment tool 200 is positioned relativeto the spindle axis 54 and the drum support 18 is positioned relative tothe alignment tool 200. This particular embodiment is shown in FIG. 4C.Following step 512, the process flow proceeds to step 506 where theupper drum 12 is aligned relative to the spindle axis 54. As was statedpreviously, in most cases, the upper drum is removed when aligning thedrum support, and therefore, the upper drum must be repositioned on thedrum assembly after aligning the drum support.

As should be appreciated, when the process flow ends, conventionalpost-alignment steps are performed. For example, some post-alignmentsteps may include reinstalling the brush/slip ring assembly, the upperdrum cover and/or the rotary head cleaner assembly. In addition, otherpost-alignment steps may include reinstalling the transport trim cover,the elevator cover, and/or the top machine cover. These post-alignmentsteps are readily understood by those skilled in the art and for thesake of brevity will not be discussed in greater detail.

FIG. 7 is a flow diagram illustrating a drum alignment procedure 520, inaccordance with another embodiment of the present invention. Prior tostarting the alignment procedure 520 conventional pre-alignment stepsmay be performed (see above). The alignment procedure 520 begins at step522 where the alignment or eccentricity of the upper drum 12 is checkedrelative to the spindle axis 54. This is typically accomplished using anindicator unit such as a dial indicator or the indicator tool 100 shownin FIG. 3. Following step 522, the process flow proceeds to step 524where a determination is made as to whether the upper drum 12 is aligned(yes) or mis-aligned (no). If the determination is that the upper drum12 is aligned (or eccentric) then the process flow ends. If thedetermination is that the upper drum is mis-aligned (or non-eccentric)then the process flow proceeds to step 530. In general, thedetermination is made (as the indicator tool is rotated) by decidingwhether or not the deviation of the probe is within a desired limit.

In step 530, the drum support is aligned relative to the spindle axis54. This is generally accomplished by adjusting the position of thelower drum support 38 relative to the spindle axis 54. In oneembodiment, the position of the lower drum support is adjusted byrepositioning the lower drum support 38 relative to the lower drum 16.This may be accomplished by loosening the lower drum screws 42, movingthe lower drum support 38 to the desired position, and tightening thelower drum screws 42 while maintaining the desired position. Followingstep 530, the process flow proceeds to step 532 where the alignment ofthe upper drum 12 is checked. This step is analogous to step 522 above.Following step 532, the process flow proceeds to step 534 where adetermination is made as to whether the upper drum 12 is aligned (yes)or mis-aligned (no). This step is analogous to step 524 above. Forexample, if the determination is that the upper drum 12 is aligned (oreccentric) then the process flow ends. If the determination is that theupper drum 12 is mis-aligned (or non-eccentric) then the process flowproceeds to step 536.

In step 536, the upper drum is aligned relative to the spindle axis. Inone embodiment, the position of the upper drum 12 is adjusted byrepositioning the upper drum support 36 relative to the lower drumsupport 38. This may be accomplished by loosening the upper drum supportscrews 40, moving the upper drum 12 to the desired position, andtightening the upper drum support screws 40 while maintaining thedesired position. Following step 536, the process flow proceeds to step522 where the alignment of the upper drum 12 is checked relative to thespindle axis 54. It should be noted that several iterations of checkingthe alignment and aligning may be needed. When the process flow ends,conventional post-alignment steps are performed (see above).

FIG. 8 is a flow diagram illustrating an alignment checking procedure540, in accordance with one embodiment of the present invention. By wayof example, alignment checking procedure 540 may generally correspond tosteps 502, 508, 522, or 532 of FIGS. 6 and 7. In general, the alignmentchecking procedure 540 is arranged to check the alignment oreccentricity of the upper drum 12 relative to the spindle axis 54. Thealignment checking procedure 540 begins at step 542 where the rubberstoppers 175 are placed in the holes 71 located on the top surface ofthe upper drum 12 (holes closest to the drum support 18). The rubberstoppers 175, when positioned in the holes 71, are configured to preventan indicator tool from contacting the drum support 18. This is done toprotect both the indicator tool and the drum support 18 during rotationof the indicator tool about the spindle axis 54.

Following step 542, the process flow proceeds to step 544 where anindicator tool is connected to the spindle assembly. In one embodiment,the indicator tool corresponds to the indicator tool 100 of FIG. 3. Inthis embodiment, the holding device 104, and more particularly theslotted mount 112, of the indicator tool 100 is placed in the centerguide 34 of the spindle pad 48. As shown in FIG. 3C, the slotted mount112 extends through the cavity 32 in the inner drum 14 where the slipring was just removed. During placement, the locking arm 108 of theindicator tool 100 is moved from a first position to a second positionto secure the slotted mount 112 in the guide 34. Once secured, theindicator tool 100 rotates about the spindle axis 54 via the spindle pad48. In one implementation, the measuring probe 120 of the indicator tool100 is pre-set to contact the outer peripheral surface 13 of the upperdrum 12 and to allow full dial movement while the indicator tool 100 isrotated from a first point to a second point (i.e., from one rubber stopto the other rubber stop). However, if an adjustment is needed, the setscrew 130 on the housing 102 may be loosened and the measuring devicemay be slid back and forth until there is enough range, i.e., until thetip of the indicator tool abuts the outer peripheral surface of theupper drum. In most cases, the probe 124 is slid back and forth untilthe desired measurement range is provided.

Following step 544, the process flow proceeds to step 546 where theindicator unit is rotated (counter clockwise) to check the eccentricity(TIR) of the upper drum 12 to the spindle axis 54. When using theindicator tool 100, the indicator tool 100 is first rotated (clockwise)to a first rubber stop and the gauge is set to zero. Thereafter, theindicator tool 100 is rotated (counter clockwise) from the first rubberstop to the second rubber stop so as to determine the amount ofdeviation along the outer peripheral surface 114 of the upper drum 12relative to the spindle axis 54. Once the amount of deviation has beendetermined, the indicator tool 100 is removed from the guide 34 byloosening the locking arm 108 and lifting the indicator tool 100.

FIG. 9 is a flow diagram illustrating an upper drum alignment procedure550, in accordance with one embodiment of the present invention. By wayof example, the upper drum alignment procedure 550 may generallycorrespond to steps 506 and 536 shown in FIGS. 6 and 7. This procedureis implemented when the eccentricity (TIR) of the upper drum is off orout of alignment, e.g., if not able to center the upper drum assemblywithin 0.0002 inches. Prior to starting the alignment procedure 550conventional pre-alignment steps may be performed. For example, it maybe necessary to verify that the leaf spring 45 is secure and adequatetension is applied to support the upper drum. The upper drum alignmentprocedure 550 begins at step 552 where the upper drum support screws 40,which hold the upper drum support 36 to the lower drum support 38, areslightly loosened. By slightly loosed, it is meant that the screws 40are loosened to the point where the upper drum 12 has a small amount ofplay or movement relative to the lower drum support 38.

Following step 552, the process flow proceeds to step 554 where theupper drum 12 is positioned relative to the spindle axis 54. That is,once the screws 40 have been loosened, the upper drum is moved oradjusted until it is centered about the spindle axis 54. In oneembodiment, the adjustment is implemented by hand. In anotherembodiment, the adjustment is implemented with a fixture. By way ofexample, the fixture 350 shown in FIG. 5 may be used. In either case,adjustments are typically made by measuring the displacement of theupper drum relative to the spindle axis and moving the upper drum toadjust for the displacement. In one embodiment, adjustments are made byrotating the indicator tool 100 slowly about the spindle axis 54,stopping the rotation in a position where the deviation is maximum, andpushing the upper drum 12 (with a finger or an adjustment screw) towardsthe measuring probe 125 from a position opposite (180 degrees) themeasuring probe 125 so that the deviation is ½ of the maximum value.

Following step 554, the process flow proceeds to step 556 where theupper drum support screws are tightened. Generally, the upper drumsupport screws 40 are tightened alternately and gradually, and in steps,to a tightening torque of about 8 Kgf.cm. For example, a first step mayinclude tightening the screws to 2 Kgf.cm, a second step may includetightening the screws to 4 Kgf.cm, and a third step may includetightening the screws to 8 Kgf.cm.

The upper drum positioning procedure 502 begins at step 600 where thealignment is checked at various positions around the periphery(circumference) of the upper drum. For example, the alignment may bechecked at the sides or the center (position of drum support) of theupper drum.

FIG. 10 is a flow diagram illustrating an upper drum positioningprocedure 570, in accordance with one embodiment of the presentinvention. By way of example, the upper drum positioning procedure 570may generally correspond to step 554 shown in FIG. 9. Prior to startingthe procedure 570 conventional pre-positioning steps may be performed.For example, it may be necessary to verify that the leaf spring 45 isbacked away from the upper drum. The upper drum positioning procedure570 begins at step 572 where the alignment of the upper drum relative tothe spindle axis is checked. By way of example, step 572 may correspondto the procedure shown in FIG. 8. In most cases, the alignment ischecked at various positions around the periphery (circumference) of theupper drum. For example, the alignment may be checked at the sides orthe center of the upper drum. In one embodiment, the indicator tool ismoved to three points along the outer peripheral surface 13 of the upperdrum 12. Referring to FIG. 3D, for example, the indicator tool 100 maybe rotated to point A, which is located just before the first rubberstopper, to point C, which is located across from the drum support 18,and to point B, which is located just before the second rubber stopper.In most cases, points A and B are 180 degrees from one another, andpoint C is 180 degrees from the center of the drum support 18. Ingeneral, the dial indicator is zeroed at point A, and rotated to pointsB and C using the measurement at point A as a base measurement.

After step 572, the process flow proceeds to step 574 where adetermination is made as to whether the side alignment is ok. In oneembodiment, the side alignment corresponds to the deviation betweenpoints A and B relative to the spindle axis. The determination isgenerally made by deciding whether or not the deviation between points Aand B is within a desired limit. In one implementation, the desiredlimit is about 0.0002 inches. If the determination is that the sidealignment is ok (i.e., the deviation is less than 0.0002 inches) thenthe process flow proceeds to step 576. If the determination is that theside alignment is not o.k. (i.e.,. the deviation is more than 0.0002inches) then the process flow proceeds to step 578.

In step 578, the side eccentricity of the upper drum is adjusted. Thisis generally accomplished by rotating the indicator tool 100 to the sideof negative displacement (e.g., the side that is closer to the spindleaxis), slightly loosening the upper drum support screws 40, and applyinga force to the outer peripheral surface 13 of the upper drum 12 in adirection towards the side of negative displacement until the deviationis ½ of the measured value. For example, if the negative displacement ison the side of point B, then a force is applied on point A to move pointA closer to the spindle axis 54 and point B further from the spindleaxis 54. In one embodiment, the force is applied by a finger of anoperator. In another embodiment, the force is applied by the adjustmentscrews 374, 376 of the fixture 350 shown in FIG. 5. For example, if thenegative displacement is on the side of the first adjustment post 370then the second adjustment screw 376 is moved towards the firstadjustment post 370. If the movement is impeded by the first adjustmentscrew 374, then the first adjustment screw 374 may also be moved in thatdirection. Several iterations of the above may be needed to find thecorrect position. For example, the adjustment screws 374, 376 may bemoved back and forth until the correct position is obtained. Once thecorrect position is obtained (e.g., deviation is zero), the upper drumsupport screws 40 may be tightened.

In step 576, a determination is made as to whether the center alignmentis ok. In one embodiment, the center alignment corresponds to thedeviation between points A and B relative to the spindle axis 54. Thedetermination is generally made by deciding whether or not the deviationat the center is within a desired limit. If the determination is thatthe center alignment is ok (i.e., the deviation is less than 0.0002inches) then the process flow proceeds ends. If the determination isthat the center alignment is moderately mis-aligned then the processflow proceeds to step 580. In one implementation, moderately mis-alignedcorresponds to a deviation between about 0.0002 inches and about 0.0005inches. If the determination is that the center alignment is badlymisaligned then the process flow proceeds to step 582. In oneimplementation, badly mis-aligned corresponds to a deviation of betweenabout 0.0005 inches and about 0.0010 inches.

In step 580, the center eccentricity of the upper drum is adjusted. Thisis generally accomplished by rotating the indicator tool to the centerposition C, slightly loosening the upper drum support screws 40, andapplying a force to the outer peripheral surface 13 of the upper drum 12in a direction towards the side of negative displacement until thedeviation is ½ of the measured value. For example, if the negativedisplacement is on the side of point C, then a force is applied on apoint D to move point D closer to the spindle axis 54 and point Cfurther from the spindle axis 54. In one embodiment, the force isapplied by a finger of an operator. In another embodiment, the force isapplied by an adjustment means, as for example, the drum support setscrew 232 located on the drum support 18 or the positioning set screws382, 384 located on the fixture 350. Several iterations of the above maybe needed to find the correct position. Once the correct position isobtained (e.g., deviation is zero), the upper drum support screws 40 maybe tightened.

In step 582, the drum support 18 is repositioned, i.e., the drum supportmay be forcing the upper drum out of position, and therefore itsposition may need to be adjusted in order to place the upper drum in thecorrect position. For example, if the point C is positioned away fromthe spindle axis then the drum support may be positioned to close to thespindle axis 54. Conversely, if the point C is positioned towards thespindle axis then the drum support may be positioned to far away fromthe spindle axis 54. Repositioning is generally accomplished byloosening the upper drum support screws 40, and uniformly moving thedrum support either positively or negatively in accordance with themeasured value. Following step 582, the process flow proceeds to step380. Once the sides and center have been adjusted, final testing of theeccentricity of the upper drum may be implemented.

FIG. 11 is a flow diagram illustrating a drum support repositioningprocedure 590, in accordance with one embodiment of the presentinvention. By way of example, this procedure may generally correspond tostep 582 in FIG. 10. The procedure generally begins at step 592 wherethe offset direction of the drum support is identified. This isgenerally accomplished by measuring the displacement of the centerposition of the upper drum relative to the spindle axis, and making adetermination as to whether the drum support needs to move towards thespindle axis or away from the spindle axis. By way of example, anindicator unit such as the indicator tool 100 shown in FIG. 3 may beused to measure the upper drum.

After step 592 the process flow proceeds to step 594 where a lower drumsupport screw 42 at a first side (e.g., 140) of the drum support 18 isslightly loosened. After step 594, the process flow proceeds to step 596where the position of the drum support 18 is adjusted at the first sideof the drum support 18. This is generally accomplished by moving thefirst side of the drum support 18 in accordance with the offsetdirection. For example, if the drum support 18 is offset such that theupper drum 12 is displaced in a positive direction (e.g., a directionaway from the spindle axis), the drum support 18 is moved in theopposite direction. Similarly, if the drum support 18 is offset suchthat the upper drum 12 is displaced in a negative direction (e.g., adirection towards the spindle axis), the drum support 18 is moved in theopposite direction. After step 596, the process flow proceeds to step598 where the lower drum support screw 42 at the first side istightened.

Following step 598, the process flow proceeds to step 600 where a lowerdrum support screw 42 at a second side (e.g., 142) of the drum support18 is slightly loosened. After step 600 the process flow proceeds tostep 602 where the position of the drum support 18 is adjusted at thesecond side of the drum support 18. This is generally accomplished bymoving the second side of the drum support 18 in accordance with theoffset direction. In most cases, the second side is moved the samedistance and direction as the first side. After step 602, the processflow proceeds to step 604 where the lower drum support screw 42 at thesecond side is tightened.

FIG. 12 is a flow diagram illustrating a drum alignment procedure 610,in accordance with one embodiment of the present invention. By way ofexample, the drum alignment procedure 610 may generally correspond tosteps 512 or 530 shown in FIGS. 6 and 7. Prior to starting the alignmentprocedure 610 conventional pre-alignment steps may be performed. Forexample, the upper drum may be removed from the drum assembly. Theprocess flow begins at step 612 where the alignment of the drum support18 relative to the spindle axis 54 is checked. This is generallyaccomplished by connecting an indicator unit to the spindle assembly,and measuring the displacement of the inner peripheral surface of thedrum support relative to the spindle axis. By way of example, theindicator tool may generally correspond to the indicator tool 100 shownin FIG. 3.

Following step 612, the process flow proceeds to step 614 where adetermination is made as to whether the drum support 18 is aligned (yes)or mis-aligned (no). If the determination is that the drum support 18 isaligned (or eccentric) then the process flow ends. If the determinationis that the drum support 18 is mis-aligned (or non eccentric) then theprocess flow proceeds to step 616. In general, the determination is made(as the indicator tool is rotated) by deciding whether or not thedeviation of the probe is within a desired limit. By way of example, ithas been found that a maximum deviation of 0.0002 inches (two divisionson the dial indicator) works well. It should be noted, however, thatthis is not a limitation and that the amount of deviation may varyaccording to the specific needs of each device.

In step 616, a determination is made as to how badly the drum support ismis-aligned. If the determination is that the drum support is badlymis-aligned then the process flow proceeds to a more detailed method ofaligning the drum support 619. If the determination is that the upperdrum is moderately mis-aligned then the process flow proceeds to step618. In general, the determination is made (as the indicator tool isrotated) by deciding whether or not the deviation of the probe is withina desired limit. By way of example, it has been found that a deviationof greater than 0.0003 inches is badly mis-aligned, and a deviationbetween about 0.0002 inches and about 0.0003 inches is moderatelymis-aligned. It should be noted, however, that this is not a limitationand that the amount of deviation may vary according to the specificneeds of each device.

In step 618, the position of the drum support 18 is adjusted relative tothe spindle axis 54. This is generally accomplished by repositioning thelower drum support 38 relative to the lower drum 16. For example, thelower drum support screws 42 may be loosened, and a force may be appliedto the drum support 18 so as to move it into the correct position, andthe lower drum support screws 42 may be tightened while maintaining thedesired position. For example, if a first side of the drum support 18 ismis-aligned then the lower drum support screw 42 corresponding to thatside may be loosened and a force may be applied to that side to improvethe eccentricity of the drum support 18 relative to the spindle axis 54.

As should be appreciated, when the process flow ends, conventionalpost-alignment steps are performed. For example, some post-alignmentsteps may include reconnecting the upper drum to the lower drum supportor tightening leaf spring so as to cause the upper drum to be biasedtowards the arc, i.e., force the drum support against the outerperipheral surface of the upper drum.

FIG. 13 is a flow diagram illustrating a drum support measuringprocedure 620, in accordance with one embodiment of the presentinvention. By way of example, the drum support measuring procedure 620may generally correspond to step 612 shown in FIG. 12. Prior to startingthe positioning procedure 620 some pre-positioning steps may beperformed. For example, the drum support set screw may be backed offfrom the drum assembly. The drum support measuring procedure 620generally begins at step 622 where an indicator tool is connected to thespindle assembly. In one embodiment, the indicator tool corresponds tothe indicator tool 100 of FIG. 3. In this embodiment, the holding device104, and more particularly the slotted mount 112 is placed in the centerguide 34 of the spindle pad 48. As shown in FIG. 3E, the slotted mount112 extends through the cavity 32 in the inner drum 14 where the slipring was just removed. During placement, the locking arm 108 of theholding device 104 is moved from a first position to a second positionto secure the slotted mount 112 in the guide 34. Once secured, theindicator tool 100 rotates about the spindle axis 54 via the spindle pad48.

Following step 622, the process flow proceeds to step 624 where anindicator tool is positioned next to the inner surface of the drumsupport (e.g., arc that abuts the upper drum). In the case of theindicator tool, this is generally accomplished by allowing the measuringdevice 106 to slide relative to the housing 102 so that the measuringprobe 120, and more particularly the contact ball 124, contacts theinner peripheral surface 39 of the drum support 18. The angle of themeasuring probe 120 may need to be adjusted if the measuring probe 120is unable to contact the inner peripheral surface 39 using the abovetechnique.

Following step 624, the process flow proceeds to step 626 where theindicator tool is rotated along the inner surface 39 of the drum support18 to check the eccentricity of the arc relative to the spindle axis 54.This is generally accomplished by rotating the contact ball 124 againstthe inner surface 39 from the first side 140 of the drum support 18 tothe second side 142 of the drum support 18. In one embodiment, themeasurement device 106 is zeroed at the first side 140, and thereafterrotated along the inner surface 39 to the second side 142 to determinethe eccentricity of the drum support 18.

FIG. 14 is a flow diagram illustrating a drum support positioningprocedure 630, in accordance with one embodiment of the presentinvention. By way of example, the drum support positioning procedure 630may generally correspond to step 618 shown in FIG. 12. The positioningprocedure 630 generally begins at step 632 where an identification ismade as to which side of the drum support 18 is positioned furthest fromthe spindle axis 54. This is generally accomplished by measuring thedisplacement of the drum support 18 at the first and second sides 140,142 of the drum support 18. For example, the first side 140 may bezeroed out and the indicator tool may be rotated to the second side 142.If the first side 140 is farther away from the spindle axis 54, thegauge of the indicator tool will show a negative displacement at thesecond side 142 of the drum support 18. If the second side 142 isfarther away from the spindle axis 154, the gauge of the indicator toolwill show a positive displacement at the second side 142 of the drumsupport 18.

After step 632, the process flow proceeds to step 634 where the lowerdrum support screw 42 on the side furthest from the spindle axis 54 isslightly loosened. After step 634, the process flow proceeds to step 636where furthest side is moved relative to the closest side so as to placethe drum support 18 in the correct position. That is, the furthest sideis moved to a position that produces a zero displacement relative to theclosest side. In one embodiment, this is accomplished by zeroing theindicator tool at the closest side, moving the indicator tool to thefurthest side and applying a force to the furthest side until there iszero displacement. In one implementation, the force is produced by afinger of an operator. In another implementation, the force is produceby a positioning set screw, as for example, the positioning set screws382 and 384 of the fixture 350 shown in FIG. 5. By way of example,depending on the side that needs to be moved towards the spindle axis54, one of the positioning set screws 382, 384 may be actuated to engageand force the furthest side to the correct position. If the furthestside is moved to far, the drum support set screw 232 may be used to backaway the furthest side. Several iterations may be conducted until thecorrect position is finally obtained. After step 636, the process flowproceeds to step 638 where the lower drum support screw 42 that waspreviously loosened is tightened while maintaining the correct position.

FIG. 15 is a flow diagram illustrating a drum support alignmentprocedure 660, in accordance with one embodiment of the presentinvention. By way of example, the drum support alignment procedure 660may generally correspond to steps 512, 530 or 619 shown in FIGS. 6, 7and 12. This procedure is generally implemented because the drum support18 is too far out of position to adjust the upper drum 12. The drumsupport alignment procedure 660 begins at step 662 where the upper drum12 is removed from the lower drum support 38 of the drum support 18.This is generally accomplished by loosening the leaf spring knob 73(about 4 turns), removing the upper drum support screws 40, and liftingthe upper drum 12 away from the lower drum 16. Care should be taken notto damage the tape running surface (i.e., outer peripheral surface 116)of the upper drum 12, the lower edge portion of the upper drum 12, thebottom surface of the upper drum support 36, the top surface of thelower drum support 38, and the upper edge of the lower drum 16.

Following step 662, the process flow proceeds to step 664 where theinner drum 14 is removed from the spindle pad 48. This is generallyaccomplished by fully loosening the inner drum screws 28 and lifting theinner drum 14 at an incline away from the spindle pad 48. Care should betaken not to damage the top surface of the upper drum support 38.

Following step 664, the process flow proceeds to step 666 where thelower drum support 38 is repositioned away from the lower drum 16. Thisis generally accomplished by slightly loosening the lower drum supportscrews 42, sliding the lower drum support 38 away from the outerperiphery of the lower drum 16, and re-tightening the lower drum supportscrews 42. As should be appreciated, this provides a clearance for usingthe drum alignment tool 200.

Following step 666, the process flow proceeds to step 668 where thealignment tool 200 is positioned on the spindle pad 48. This isgenerally accomplished by placing the alignment tool 200 over the guide34 and gently on the flanges 50 of the spindle pad 48, aligning theinner drum screws 28 with the flanges 50 of the spindle pad 48 andslightly tightening the inner drum screws 28 and confirming that noabnormal sounds occur when rotating the alignment tool 200 about thespindle axis 54.

Following step 668, the process flow proceeds to step 670 where the drumalignment tool 200 is aligned relative to the spindle axis 54. This istypically accomplished using a measuring device including a measuringprobe. In one embodiment, the measuring device corresponds to a dialindicator. In another embodiment, the measuring device corresponds tothe measuring device 106 of the indicator tool 100. In general, themeasuring device is fixedly positioned relative to the spindle axis 54and the measuring probe is set at the reference surface 206 of the upperplate 208. In one embodiment, the drum assembly is placed in the fixture350 and therefore the measuring device may be placed on the measuringpost 388. The alignment or eccentricity of the drum alignment tool 200is generally determined by rotating the alignment tool 200 (about thespindle axis 54) relative to the fixed measuring device. If thealignment tool 200 is correctly positioned within desired limits thenthe inner drum screws 28 may be tightened. If on the other hand, thealignment tool 200 is mis-aligned, then the alignment tool may berepositioned until it is the correct position. In one embodiment, ameasuring device, which is supplied by the manufacturer, and which iscoupled to the video recorder, is used to measure the alignment of thealignment tool 200.

Following step 670, the process flow proceeds to step 672 where thelower drum support 38 is repositioned next to the alignment tool 200.This is generally accomplished by slightly loosening the lower drumsupport screws 42, sliding the lower drum support 38 into contact withthe alignment tool 200 such that the inner peripheral surface 39 of thelower drum support 38 contacts the reference surface 206 of thealignment tool 200, applying a biasing force to the lower drum support38 to press it against the reference surface 206 of the alignment tool200, and tightening the lower drum support screws 42. In one embodiment,the biasing screw 122 of the drum alignment tool 200 is used to applythe biasing force. In this embodiment, the insert 212 of the alignmentbracket 218 is positioned at the center of the alignment plate 202, theflange 220 is radially aligned with the drum support 18 and the biasingscrew 122 is turned to advance the ball 225 against the outer peripheralsurface of the drum support 18 such that a biasing force is exerted bythe ball on the drum support 18.

Following step 672, the process flow proceeds to step 674 where thealignment tool 200 is removed from the spindle pad 48. This is generallyaccomplished by fully loosening the inner drum screws 28 and lifting thealignment tool 200 away from the spindle pad 48. Care should be takennot to damage the top surface of the upper drum support 38.

Following step 674, the process flow proceeds to step 676 where thealignment of the upper drum 12 (per drum support 18) is verified. Thisis generally accomplished by reinstalling the upper drum 12, checkingthe alignment of the upper drum 12 relative to the spindle axis 54, anddetermining whether the upper drum 12 is aligned or mis-aligned. Ifmisaligned, a determination is typically made as to whether themis-alignment can be corrected by repositioning the upper drum. If not,the process flow returns to step 662. If it can be corrected or if it isaligned, the upper drum 12 is removed, and the process flow proceeds tostep 678.

In step 678, the inner drum 14 is positioned on the spindle pad 48. Thisis generally accomplished by radially aligning the inner drum 14 withthe drum support 18 (via holes), aligning the guide 34 with apositioning hole of the inner drum 14, placing the inner drum 14 gentlyon the flanges 50 of the spindle pad 48, tightening the inner drumscrews 28 tentatively and equally while pushing from above, and rotatingthe inner drum (counter clockwise) so as to confirm that no abnormalsounds occur when rotating. Care should be taken not to touch thecontact points, flanges, audio TC head, peripheral tape guides, and drumsupport when installing the inner drum 14.

Following step 678, the process flow proceeds to step 680 where theinner drum 14 is aligned relative to the spindle axis 54. This isgenerally accomplished using a measuring device and following standardalignment procedures associated with the specific design of the drumassembly 10. Any suitable measuring device may be used. In general, themeasuring device is fixed relative to the rotating inner drum. In oneembodiment, the measuring device corresponds to the measuring device 106shown in FIG. 3. For example, the measuring device 106 may be used withthe fixture 350 shown in FIG. 5. In another embodiment, a measuringdevice associated with a dial indicator is used. In this embodiment, thedial indicator is positioned on a chassis in the video recorder 2.

The standard procedure generally begins by positioning the measuringprobe of the measuring device next to an alignment surface (e.g., outerperipheral surface) of the inner drum 14. By way of example, thealignment surface may correspond to the outer peripheral surface of theinner drum 14 just above the head assembly 15. After positioning themeasuring probe next to the alignment surface, the gauge of themeasuring device is zeroed. After zeroing the gauge, the inner drum 14is slowly rotated (counterclockwise) around the alignment surface of theinner drum 14 to confirm that the pointer deviation of the toolsatisfies the specification in one complete turn of the inner drum. Oncesatisfied, the inner drum screws 28 are gradually tightened in aspecific order so as to secure the inner drum 48 to the spindle pad 48.By way of example, the screws may be tightened to 4 kgf-cm and in theorder B-A-D-C as shown in FIG. 4G.

Once tightened, the inner drum 14 is slowly rotated around the alignmentsurface of the inner drum 14 to reconfirm that the pointer deviation ofthe tool satisfies the specification in one complete turn of the innerdrum 14. Thereafter, the inner drum screws 28 are gradually tightened ina specific order. For example, the inner drum screws may be furthertightened to 8 kgf-cm in the order B-A-D-C. Once tightened, the innerdrum 14 is slowly rotated around the alignment surface of the inner drum14 to reconfirm that the pointer deviation of the tool satisfies thespecification in one complete turn of the inner drum 14.

If the specification is not satisfied in any of the above steps, thenrepositioning steps are typically performed. Repositioning stepsgenerally include rotating the inner drum slowly (counterclockwise) tothe position where the pointer deviation is minimum, pushing the innerdrum (board cover) in the position opposite the measuring probe (e.g.,180 degrees) so that the pointer deviation is =b {fraction (1/2)} of themaximum value, and confirming that the specification is satisfied. Inone embodiment, the pushing is implemented with a finger of an operator.In another embodiment, the pushing is implemented using the fourthadjustment screw 398 of the fixture 350.

After step 680, the process flow proceeds to step 682 where the upperdrum 12 is reconnected to the lower drum support 38.

FIG. 16 is a flow diagram illustrating an alignment tool alignmentprocedure 700, in accordance with one embodiment of the presentinvention. By way of example, the alignment tool alignment procedure 700may generally correspond to step 670 shown in FIG. 15. The alignmentprocedure 700 begins at step 702 where the alignment or eccentricity ofthe alignment tool 200 is checked relative to the spindle axis 54. Thisis typically accomplished using a measuring device that includes ameasuring probe. In one embodiment, a measuring device corresponding toa dial indicator such as the dial indicator shown in FIG. 4 may be used.Referring to FIG. 4E, for example, the measuring device 300 may be fixedat a known position 306 and the measuring probe 303 may be placed nextto the reference surface 206 of the alignment tool 200. In oneembodiment, the drum assembly 10 is placed back into the video recorderbefore aligning the alignment tool 200 and thus the known position mayrepresent a portion of the video recorder. In another embodiment, themeasuring device 106 of FIG. 3 may be used along with the fixture 350 ofFIG. 5. Referring to FIG. 5, for example, the measuring device 106 maybe placed on the measuring post 388, and the measuring probe 120 may beplaced next to the reference surface 206 of the alignment tool 200. Inthis manner, the drum assembly 10 does not have to be put back into thevideo recorder 2 in order to align the alignment tool 200.

In most cases, the reference surface 206 and the measuring probe arecleaned prior to starting the alignment procedure 700. Once positioned,the alignment or eccentricity of the alignment tool 200 is measured viathe measuring probe by rotating the alignment tool 200 about the spindleaxis 54. In most cases the alignment tool 200 is rotated one completeturn.

Subsequent to step 702, the process flow proceeds to step 702 where adetermination is made as to whether the alignment tool 200 is aligned(yes) or misaligned (no). If the determination is that the alignmenttool 200 is aligned (or eccentric) then the process flow proceeds tostep 706. If the determination is that the alignment tool 200 ismis-aligned (or non eccentric) then the process flow proceeds to step708. In general, the determination is made (as the alignment tool isrotated) by deciding whether or not the deviation of the probe (via agauge) is within a desired limit.

In step 708, the position of the alignment tool 200 is adjusted relativeto the spindle axis 54. This is generally accomplished by rotating thealignment tool 200 slowly about the spindle axis 54, stopping therotation in a position where the deviation is minimum, and pushing thealignment tool 200 towards the measuring probe from a position opposite(180 degrees) the measuring probe so that the deviation is ½ of themaximum value. In one embodiment, the alignment tool is pushed with afinger. In another embodiment, the alignment tool is pushed using thethird adjustment screw 390 of the fixture 350. Following step 708, theprocess flow proceeds back to step 702 where the alignment oreccentricity of the alignment tool 200 is measured via the measuringprobe by rotating the alignment tool 200 about the spindle axis 54.

In step 706, the inner drum screws 28 are gradually tightened in aspecific order. In one embodiment, the inner drum screws are tightenedto 4 kgf-cm. In another embodiment, the screws 28 are tightened in analternating and opposite order where screw 28A is tightened first, screw28C is tightened second, screw 28B is tightened third, and screw 28D istightened fourth. Following step 706, the process flow proceeds to step710 where the alignment or eccentricity of the alignment tool 200 ismeasured via the measuring probe by rotating the alignment tool 200about the spindle axis 54. Step 710 is analogous to step 702 above.

Following step 710, the process flow proceeds to step 712 where adetermination is made as to whether the alignment tool 200 is aligned(yes) or mis-aligned (no). If the determination is that the alignmenttool 200 is aligned (or eccentric) then the process flow proceeds tostep 714. If the determination is that the alignment tool 200 ismis-aligned (or non eccentric) then the process flow proceeds back tostep 708. In general, the determination is made (as the alignment toolis rotated) by deciding whether or not the deviation of the probe (viagauge) is within a desired limit. Step 712 is analogous to step 704above.

In step 714, the inner drum screws 28 are further tightened. In oneembodiment, the inner drum screws 28 are tightened to 8 kgf-cm. Inanother embodiment, the screws 28 are tightened in an alternating andopposite order where screw 28A is tightened first, screw 28C istightened second, screw 28B is tightened third, and screw 28D istightened fourth. Following step 714, the process flow proceeds to step716 where the alignment or eccentricity of the alignment tool 200 ismeasured via the measuring probe by rotating the alignment tool 200about the spindle axis 54. Step 716 is analogous to step 702 above.Following step 716, the process flow proceeds to step 718 where adetermination is made as to whether the alignment tool 200 is aligned(yes) or mis-aligned (no). If the determination is that the alignmenttool 200 is aligned (or eccentric) then the process flow ends. If thedetermination is that the alignment tool 200 is mis-aligned (or noneccentric) then the process flow proceeds back to step 708. In general,the determination is made (as the alignment tool is rotated) by decidingwhether or not the deviation of the probe (via gauge) is within adesired limit. Step 718 is analogous to step 704 above.

The advantages of the invention are numerous. Different embodiments orimplementations may have one or more of the following advantages. Oneadvantage of the invention is that the upper drum can be aligned to thelower drum thus improving the tape path, i.e., reduce tape wear. Anotheradvantage of the invention is that more consistent wear and improvedlongevity of the video recorder and the drum assembly is achieved thusreducing costs. Another advantage of the invention is that an alignedupper drum reduces sticktion, i.e., tape sticking to side of drumassembly. Another advantage of the invention is that head to tapecontact can be optimized. Another advantage of the invention is that RFperformance can be maximized.

While this invention has been described in terms of several preferredembodiments, there are alterations, permutations, and equivalents, whichfall within the scope of this invention. For example, although the toolsand methods of the present invention have been directed at drumassemblies of video recorders associated with digital beta formats (DVW,DNW, HDW), it should be noted that this is not a limitation and that thetools and methods may also be applied to drum assemblies of videorecorders using other formats, as for example, other digital formats(D2/D1) or analog beta formats (SP Beta).

It should also be noted that there are many alternative ways ofimplementing the methods and apparatuses of the present invention. Forexample, although the indicator tool was shown as connecting to thespindle assembly, it may be configured to couple to other components ofthe drum assembly. In one embodiment, for instance, the indicator toolmay include a holding mechanism that connects to the drum support. Inone implementation of this embodiment, the holding mechanism may includea pair of holes for allowing the indicator tool to be secured to thedrum support using the upper drum support screws and the housing may beelongated so as to place. In a case such as this, the housing may bearranged to extend to the side opposite the drum support so as to placethe measurement device in a location for measuring the inner drum oralignment tool when they are rotated about the spindle axis.

It is therefore intended that the following appended claims beinterpreted as including all such alterations, permutations, andequivalents as fall within the true spirit and scope of the presentinvention.

What is claimed is:
 1. An indicator tool for checking the alignment of acomponent of a drum assembly, the drum assembly including a spindleassembly having a rotatable component that rotates about an axis, thedrum assembly being used in a video recording device, said indicatortool comprising: a housing; a holding mechanism coupled to said housingand securing said indicator tool to said rotatable component of saiddrum assembly so as to allow said indicator tool to rotate about saidaxis; and a measuring device coupled to said housing and measuring theeccentricity of said component when said indicator tool is secured tosaid rotatable component of said spindle assembly.
 2. The tool asrecited claim 1 wherein said component is a drum of said drum assembly,and wherein said measuring device is used to measure the eccentricity ofsaid drum relative to said axis.
 3. The tool as recited claim 1 whereinsaid component is a drum support, and wherein said measuring device isused to measure the eccentricity of said drum support relative to saidaxis.
 4. The tool as recited claim 1 wherein said holding mechanismincludes a locking rod threadably coupled to said housing, a locking armstructurally coupled to said locking rod, and a slotted mountmechanically disposed between said locking rod and said housing, saidslotted mount being adapted for insertion into a guide of said drumassembly, wherein when the locking arm is rotated, the locking rod moveswithin the housing causing the slotted mount to bulge outwardly, whichas a result secures the slotted mount within said guide of said drumassembly.
 5. The tool as recited claim 1 wherein said housing includes achannel for slidably receiving said measuring device.
 6. The tool asrecited claim 1 wherein said measuring device includes an indicator unitfor housing the inner workings of said measuring device, a measuringprobe for contacting a surface to be measured, and an output gauge foroutputting the displacement of said surface being measured.
 7. Theindicator tool as recited in claim 2 wherein said drum corresponds to anupper drum of said drum assembly.
 8. The tool as recited claim 1 whereinsaid drum assembly corresponds to models DVW, DNW, HDW series.
 9. Anindicator tool for checking the alignment of a drum assembly aswociatedwish a video recording device, the drum assembly including a lower drumthat is connected to base, an upper drum that is connected to the lowerdrum via a drum support, a spindle assembly that is rotatably coupled tothe base, and an inner drum attached to the spindle assembly, thespindle assembly including a guide post and rotating about a spindleaxis, the inner drum including a plurality of record/reproduce headsconfigured for video recording, the indicator tool comprising: ahousing; a holding mechanism coupled to said housing, said holdingmechanism including a mount that is releasably mountable to the guidepost of said spindle assembly so as to enable the indicator tool torotate about the spindle axis; and a measuring device coupled to saidhousing and configured to measure the displacement of a surface of saiddrum assembly relative to the spindle axis, said measuring deviceincluding a probe configured to contact at least an outer peripheralsurface of the upper drum or an inner peripheral surface of the drumsupport, the probe being biased towards the peripheral surfaces in adirection substantially perpendicular to the spindle axis, whereindeviations along the peripheral surfaces are ascertained relative to thespindle axis when the indicator tool is rotated about the spindle axisand the probe is in contact with one of the peripheral surfaces.
 10. Amethod of checking the eccentricity of a drum assembly associated with avideo recording device, said drum assembly including a drum componentand a spindle component, said drum component having a surface, saidspindle component rotating about a spindle axis, said method comprising:providing an indicator tool having a holding mechanism mountable to saidspindle component and a measuring device including a probe for engagingthe surface of said drum component; mounting said indicator tool on saidrotatable component of said drum assembly such that said indicator toolmay rotate about said spindle axis via said spindle component; andmeasuring the displacement of the surface of said drum componentrelative to said spindle axis, said measuring including positioning saidprobe along the surface of said drum component and thereafter rotatingsaid indicator tool about said spindle axis.